The present embodiments relate to a head coil for a magnetic resonance tomography (MRT) system.
Magnetic resonance tomography devices for examining objects or patients using magnetic resonance tomography (MRT, MRI) are described, for example, in DE 10314215B4.
In MR tomography, images with a high signal-to-noise ratio (SNR) may be recorded with local coils. The local coils are antenna systems that are attached in the immediate vicinity of (anterior) or below (posterior) the patient. During an MR measurement, the excited cores induce a voltage into the individual antennae of the local coil. The induced voltage is amplified with a low noise preamplifier (LNA, preamp) and is forwarded over a cable to receive electronics. In order to improve the SNR in, for example, highly resolved images, high field systems are used (e.g., 1.5 T to 12 T and more). Since more individual antennae may be connected to an MR receiving system than there are receivers present, a switching matrix (e.g., RCCS) is integrated between receiving antennae and receiver. This routes the currently active receiving channels (e.g., the receiving channels lying precisely within the field of view of the magnet) to the existing receiver. More coil elements than there are receivers present may thus be connected, since with a whole body coverage, only the coils that are in the field of view (FoV) and/or in a homogeneity volume of the magnet have to be read out.
For example, an antenna system that may include one or several antenna elements or coil elements (e.g., an array coil) is referred to below as “coil” (e.g., a local coil). The individual antenna elements are, for example, embodied as loop antennae (e.g., loops), butterfly coils or saddle coils. A coil includes the coil elements, a preamplifier, further electronics (e.g., cable traps), cabling, a housing and may include a cable with a plug, by which the coil is connected to the MRT system. The receiver (RX) attached on the system side filters and digitizes the signal received by the local coil and transfers the data to the digital signal processing. The digital signal processing may derive an image or a spectrum from the measurement and provides the image or spectrum to the user for diagnosis.
In order to position patients with abnormal changes to the cervical spine (e.g., Bechterew, torticollis, hyperkyphosis or accident patients in the head coils), the head coil may be raised in the rear head area, since the patient is not in the position to lie his/her head flat in the coil. Contacting systems use a defined assignment between the patient couch and the head coil, for example, with direct contacting of the head coil into the patient couch or with alternative contacting variants, such as capacitive coupling between the patient couch and the head coil. With contacting systems, a movement of the coil relative to the patient couch in an inserted plugged-in state may not be possible. The coil and the patient couch form a fixed plug-in unit.
For coils that are in direct contact with the patient couch (e.g., the Siemens head coil for the Aera and Skyra systems), or for alternative contacting possibilities with a fixed assignment between the patient couch and the coil, a movement of the coil relative to the patient couch may be enabled for Bechterew patients, for example. Higher positioning of the pelvis is, for example, achieved by transferring the patient with suitable positioning materials. Head coils with a correspondingly long external connecting line are rotated about a center of rotation that is located below the neck region of the patient. This results in a tilting movement of the coil. A further alternative solution is the underlaying of wedge-shaped parts below the head coil.